3♠ is minor suit Stayman.
I think this is a problem in hand evaluation which Gib doesn't do it just counts points.
Hand evaluation says this hand good enough for 6 if not off 2 Aces so stuck with Gerber

This 4NT bid is in the critical error category--not just a minor misbid. Even with a square 12 GIB should skip the quantitative and just bid 6 (20-21 + 12 = 32-33). With the diamond suit as it is, it should be considering a grand.

Even with a square 12 GIB should skip the quantitative and just bid 6 (20-21 + 12 = 32-33).

I don't think a quantitative invite with 12 flat is unreasonable. If all declarers on BBO were to play like Meck or Bessis then lower the invite to 11, but I see no good reason to eliminate it - just don't make it with shapely hands.

This 4NT bid is in the critical error category--not just a minor misbid. Even with a square 12 GIB should skip the quantitative and just bid 6 (20-21 + 12 = 32-33). With the diamond suit as it is, it should be considering a grand.

Would it be unlucky if 2NT opener had 20 HCP and you are missing 2 aces or a critical error?

GIB doesn't have a way to transfer to diamonds. I think Stayman followed by 4♦ is the normal way to bid this hand.

But I am not sure if this helps yourself and partner more than it helps opps. Probably just let the sims decide whether 6♦ or 6NT is better and then bid it.

OK, Gerber can do little harm, I suppose. Not for checking aces (partner is exceedingly unlikely to have zero aces) but to see if they can double 4♣. If so, you can then decide to bid 6♦ (or 5 if missing two aces).

... most of the new ideas I get are pretty "boring", mostly focusing on constructive methods rather than destructive ones --- Kungsgeten

GIB doesn't have a way to transfer to diamonds. I think Stayman followed by 4♦ is the normal way to bid this hand.

But I am not sure if this helps yourself and partner more than it helps opps. Probably just let the sims decide whether 6♦ or 6NT is better and then bid it.

OK, Gerber can do little harm, I suppose. Not for checking aces (partner is exceedingly unlikely to have zero aces) but to see if they can double 4♣. If so, you can then decide to bid 6♦ (or 5 if missing two aces).

I'm with the Gerber bidders all the way, and as you say, it costs nothing to find out about the off chance you could be missing 2 aces (and have the defense cash them both with one in each hand). I'm not letting GIB off on quantitative with this hand, however.